Bus systems are in use in a wide variety of technical applications. In particular field buses, for example the PROFIBUS (PROcesFieldBUS) according to DIN 19245 (EN 50170 since 1996) are widely used, for example, in automation technology, for the transmission of data over relatively long paths. In contrast to most systems which transmit data in a parallel fashion, the PROFIBUS is a serial bus system in which data is transmitted serially. Field buses have wide-ranging fields of application because they can be connected to, and operated with, both simple and complex components (stations). Furthermore, they are advantageous in terms of the low connection costs and reduced expenditure on cabling. Additional advantages are short reaction times and simple protocols which make field buses real-time-capable. Other factors to note are the high degree of immunity to faults, even over large distances, simple integration in the existence of the systems and the ease with which the respective elements are made independently irreplaceable.
An example of such a field bus is the PROFIBUS according to DIN 19245, which can be divided into various hierarchical layers on the basis of different functionalities and modes of operation. Part 1 of DIN 19245 in this case defines the PROFIBUS layers 1 and 2, where the fieldbus datalink (FDL) is defined, for example. An example of the bus system of these layers is illustrated in FIG. 1. Part 2 of DIN 19245 defines the PROFIBUS layer 7 and contains the fieldbus message specification (FMS). Part 3 of DIN 19245 defines the PROFIBUS DP (decentralized peripherals) which comprises the PROFIBUS FDL of layers 1 and 2 and defines service interfaces and data interfaces for exchanging data with external peripheral data.
A fieldbus such as the PROFIBUS DP usually comprises one or more active stations and a plurality of passive stations. The active and passive stations or components are configured here in a master-slave relationship. This means that the active components actuate the passive components and/or read data in and out. The passive components operate only after being actuated by the active components. The problem with such fieldbuses is the reading out of the current data to external peripherals, such as for example computers. Existing systems are slow, inefficient and complicated.